With increasing emphasis on engaging patients as partners in and often drivers of their health and health care, patient engagement is seen as a necessary component in achieving the triple aim of improved experience of care, improved health of populations, and lower per capita health care costs. The goal of this research is to develop a patient-focused engagement measure that improves our understanding of patient engagement from the perspective of patients and clinicians, and that allows for identification of individual differences in the dimensions of patient engagement. As healthcare policies increasingly incentivize patient-centered and patient-engaged care, there is a critical need for the development and validation of such a measure. We propose a multi-phase study aimed at developing and implementing a psychometrically valid instrument that measures the capacity of patients to engage in their health care, the Total Engagement and Activation Measure (TEAM). Accomplishment of this major study aim will also involve three specific aims: 1) development of a conceptual model of patient engagement that reflects shared perspectives of patients and clinicians about engagement and takes into account the context in which engagement happens; 2) utilization of the NIH PROMIS methodology to conduct Instrument Development and Validation (IDV) for this new measure of the capacity for patient engagement; and 3) administration of this newly developed measure in the `real world' setting of a large academic medical center to examine variability in the components of patient engagement across different subgroups of hospitalized patients. Development of the comprehensive TEAM measurement tool will enable future exploration of a series of ongoing and significant research questions such as how shifts in policy, provider remuneration, and new technologies support the kind of care that facilitates patient engagement. Achieving a greater understanding of the concept of patient engagement and its measurement will clarify the most effective ways to support patients in becoming partners in their care in order to improve and maintain their health, and subsequently allow for the identification of actionable points of intervention that can be leveraged in future studies and initiatives aimed at increasing patient engagement.